Metallic radionuclides: Applications in diagnostic and therapeutic nuclear medicine

Nuclear Medicine is a medical modality that utilizes radioactivity (radiopharmaceutical) to diagnose and treat disease. Radiopharmaceuticals contain a component which directs the radionuclide to the desire physiological target. For diagnostic applications, these nuclides must emit a gamma ray that can penetrate the body and can be detected externally while for therapeutic purposes nuclides are preferred that emit beta particles and deliver highly localized tissue damage. sup 6 sup 7 Ga citrate is employed to detect chronic occult abscesses, Hodgkin's and non-Hodgkin's lymphomas, lung cancer, hepatoma and melanoma and localizes in these tissues utilizing iron-binding proteins. sup 2 sup 0 sup 1 Thallous chloride, a potassium analogue, used to diagnosis coronary artery disease, is incorporated in muscle tissue via the Na sup + -K sup + -ATPase. sup 1 sup 1 sup 1 In labeled autologous white blood cells, used for the diagnosis of acute infections and inflammations, takes advantage of the white cell's role in fighting infections. sup 1 sup 1 sup 1 In is incorporated in other radiopharmaceuticals e.g. polyclonal IgG, OncoScint CR/OV, OctreoScan and Myoscint by coupling diethylenetriaminepentaacetic acid, a chelate, covalently to these molecules. OncoScint CR/OV and Myoscint localize by antigen-antibody interactions while OctreoScan is taken up by malignant cells in a receptor based process. Polyclonal IgG may share some localization characteristics with sup 6 sup 7 Ga. sup 8 sup 9 Sr, a pure beta emitter, is used for palliation of bone pain due to metastatic bone lesions. Bone salts [Ca(PO) sub 4] are increased in these lesions and this radionuclide is taken up similarly to Ca sup 2 sup +. sup 1 sup 8 sup 6 Re and sup 1 sup 5 sup 3 Sm bound to polydentate phosphonate chelates are used similarly and follow the phosphate pathway in lesion incorporation. (author)